[Qemu-devel] [PATCH v3 10/26] tcg: don't explicitly save globals and temps

[Aurelien Jarno <aurelien@aurel32.net>]

The liveness analysis ensures that globals and temps are at the correct
state at a basic block end or with an op with side effects. Avoid
looping on all temps, this can be time consuming on targets with a lot
of globals. Keep an assert in debug mode.

Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
---
 tcg/tcg.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/tcg/tcg.c b/tcg/tcg.c
index 8333667..840e252 100644
--- a/tcg/tcg.c
+++ b/tcg/tcg.c
@@ -1648,8 +1648,14 @@ static inline void temp_sync(TCGContext *s, int temp, TCGRegSet allocated_regs)
    temporary registers needs to be allocated to store a constant. */
 static inline void temp_save(TCGContext *s, int temp, TCGRegSet allocated_regs)
 {
+#ifdef USE_LIVENESS_ANALYSIS
+    /* The liveness analysis already ensures that globals are back
+       in memory. Keep an assert for safety. */
+    assert(s->temps[temp].val_type == TEMP_VAL_MEM || s->temps[temp].fixed_reg);
+#else
     temp_sync(s, temp, allocated_regs);
     temp_dead(s, temp);
+#endif
 }
 
 /* save globals to their canonical location and assume they can be
@@ -1676,7 +1682,13 @@ static void tcg_reg_alloc_bb_end(TCGContext *s, TCGRegSet allocated_regs)
         if (ts->temp_local) {
             temp_save(s, i, allocated_regs);
         } else {
+#ifdef USE_LIVENESS_ANALYSIS
+            /* The liveness analysis already ensures that temps are dead.
+               Keep an assert for safety. */
+            assert(ts->val_type == TEMP_VAL_DEAD);
+#else
             temp_dead(s, i);
+#endif
         }
     }
 
-- 
1.7.10.4